Many genomes have been
sequencedIn genetics and biochemistry, sequencing means to determine the primary structure of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which succinctly summarizes much of the atomic-level structure of the sequenced molecule.-DNA sequencing:DNA...
and their gene sequences are stored in general DNA sequence databases (e.g.
GenBankThe GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. This database is produced at National Center for Biotechnology Information as part of the International Nucleotide Sequence Database Collaboration,...
) and in species specific databases (e.g. The
ArabidopsisArabidopsis is a genus in the family Brassicaceae. They are small flowering plants related to cabbage and mustard. This genus is of great interest since it contains thale cress , one of the model organisms used for studying plant biology and the first plant to have its entire genome sequenced...
Information Resource (TAIR).
The figures are views of the sequence of one (AMY1) of the approximately 25,000 genes from
Arabidopsis thalianaArabidopsis thaliana , is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, Arabidopsis is popular as a model organism in plant biology and genetics...
the Thale Cress plant.
This gene encodes an alpha
amylaseAn amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion. Foods that contain much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns some of their...
enzyme.
These images are views of the gene, cDNA, and coding sequence (
CDS-Computing and electronics:* Cadence Design Systems, an American company producing Electronic Design Automation software* Cockpit display system, in Avionics, is the Human Machine Interface by which aircrew manage the modern Glass cockpit...
) used by researchers to study it further.
Many genomes have been
sequencedIn genetics and biochemistry, sequencing means to determine the primary structure of an unbranched biopolymer. Sequencing results in a symbolic linear depiction known as a sequence which succinctly summarizes much of the atomic-level structure of the sequenced molecule.-DNA sequencing:DNA...
and their gene sequences are stored in general DNA sequence databases (e.g.
GenBankThe GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. This database is produced at National Center for Biotechnology Information as part of the International Nucleotide Sequence Database Collaboration,...
) and in species specific databases (e.g. The
ArabidopsisArabidopsis is a genus in the family Brassicaceae. They are small flowering plants related to cabbage and mustard. This genus is of great interest since it contains thale cress , one of the model organisms used for studying plant biology and the first plant to have its entire genome sequenced...
Information Resource (TAIR).
The figures are views of the sequence of one (AMY1) of the approximately 25,000 genes from
Arabidopsis thalianaArabidopsis thaliana , is a small flowering plant native to Europe, Asia, and northwestern Africa. A spring annual with a relatively short life cycle, Arabidopsis is popular as a model organism in plant biology and genetics...
the Thale Cress plant.
This gene encodes an alpha
amylaseAn amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion. Foods that contain much starch but little sugar, such as rice and potato, taste slightly sweet as they are chewed because amylase turns some of their...
enzyme.
These images are views of the gene, cDNA, and coding sequence (
CDS-Computing and electronics:* Cadence Design Systems, an American company producing Electronic Design Automation software* Cockpit display system, in Avionics, is the Human Machine Interface by which aircrew manage the modern Glass cockpit...
) used by researchers to study it further. Such research might involve seed germination or plant flavour.
cDNA
The image below shows a screenshot of the
AMY1 cDNA. This was obtained from
TAIR
Note that TAIR provide three views of the 'Nucleotide Sequence', 'full length CDS', 'full length cDNA' (Fig. 1), 'full length genomic' (Fig. 2]. In each of them the DNA alphabet is used, although strictly the CDS should be shown as RNA (AUG etc).
A typical eukaryotic gene is transcribed into an pre-mRNA that is then processed into a mature mRNA by removal of
intronAn intron is a DNA region within a gene that is not translated into protein. These non-coding sections are transcribed to precursor mRNA and some other RNAs , and subsequently removed by a process called splicing during the processing to mature RNA. After intron splicing An intron is a DNA region...
s and 5' and 3' processing.
Gene and mRNA
The mature mRNA is comprised of a 5' UTR (red)
CDS-Computing and electronics:* Cadence Design Systems, an American company producing Electronic Design Automation software* Cockpit display system, in Avionics, is the Human Machine Interface by which aircrew manage the modern Glass cockpit...
(uppercase yellow) and 3' UTR (red again) (Fig. 2). All three of these regions are
exonAn exon is a nucleic acid sequence that is represented in the mature form of an RNA molecule after either portions of a precursor RNA have been removed by cis-splicing or by two or more precursor RNA molecules have been ligated by trans-splicing. The mature RNA molecule can be a messenger RNA or...
ic (not just the protein coding sequence (CDS)).
IntronAn intron is a DNA region within a gene that is not translated into protein. These non-coding sections are transcribed to precursor mRNA and some other RNAs , and subsequently removed by a process called splicing during the processing to mature RNA. After intron splicing An intron is a DNA region...
s are shown in purple (lowercase) and are not present in the mature mRNA.
For convenience neither the 5' Cap nor 3' tail are shown in the cDNA (fig 1) although the mRNA will have them. The gene sequence is also shown in a form where the codons can be read (ATG...), rather than as the
templateDeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses. The main role of DNA molecules is the long-term storage of information...
DNA strand which is actually copied into mRNA.
This gene structure view is typical of a eukaryotic gene. Similar views of genes can be obtained for
humanHumans are bipedal primates belonging to the species Homo sapiens in Hominidae, the great ape family. They are the only surviving member of the genus Homo. Humans have a highly developed brain, capable of abstract reasoning, language, introspection, and problem solving...
, fruitfly, or
yeastYeasts are eukaryotic micro-organisms classified in the kingdom Fungi, with about 1,500 species currently described; they dominate fungal diversity in the oceans. Most reproduce asexually by budding, although a few do so by binary fission...
genes.
External links